This is a debate? Mexico's presidential face-off a scripted affair.

Mexico's presidential debate was highly structured and scripted last night, leaving little room for candid conversation on important policies like security and education.

The front-runner in Mexico's presidential race, Enrique Peña Nieto, might have movie star looks and a seemingly unbeatable lead ahead of the July 1 election, but he also has a knack for gaffes when straying from the script.

So if anything is his to lose, it is the presidential debates, the first of which took place last night in Mexico City.

His opponents tried to put him on the spot: They attacked his term as governor in the state of Mexico, and suggested that if he won, the country would return to corruption and cronyism. His party, the Institutional Revolutionary Party (PRI), ruled Mexico for 71 years, and is believed to have made pacts with drug cartels as part of their governing strategy.

But it appears that Mr. Peña Nieto held his own. He made no major fumbles that could go viral across social media, contrary to his December slip-up at a book fair when he was unable to cite any books, beyond the Bible, that influenced him.

But this probably has less to do with a new-found skill to talk off the cuff. Instead, the debate itself was highly structured, lending itself to the kinds of scripting that serves Peña Nieto well. All four presidential candidates agreed to the format beforehand, and in fact, they even knew which questions would be asked of them. Each candidate had two minutes to respond, and 90 seconds for a rebuttal.

As a result, instead of a lengthy, dynamic conservation that could push the agenda forward on the economy, security, and education, last night's debate was mostly an evening for candidates to articulate their positions (again), peppering them with attacks and counter-attacks.

“Everyone talked about what they wanted,” says Aldo Muñoz, a political analyst at Mexico State's Autonomous University. “None of the issues were talked about with profundity. So the one who wins the debate is the one who was ahead in the first place.”

And that means that Mr. Peña Nieto remains clearly out in front.

Josefina Vázquez Mota of the ruling National Action Party (PAN) has, according to most polls, been at a distant second throughout the race, and she has focused on undermining Peña Nieto's lead. Ms. Vázquez Mota pulled out an article by The Economist last night that questioned the veracity of statistics on homicides during Peña Nieto's time as governor in the state of Mexico.

She emphasized that as the country's first woman president she would represent a turn towards a more honest and sensitive government.

“I want to be president because I have the sensitivity, as a woman, to listen,” she said.

Andres Manuel Lopez Obrador from the left-leaning Democratic Revolution Party (PRD) also used visual props to attack Peña Nieto, holding up a photo showing him with a former governor whose term ended amid corruption allegations.

The PRI governed Mexico for most of the 20th century until the PAN won the presidency in 2000. All candidates are trying to paint Peña Nieto as a return to an authoritarian past, and Mr. Lopez Obrador added that voting in either the PRI or PAN would not represent true change in the nation.

"This dominant group has privatized the government," Lopez Obrador said. "Do you think things will get better if the PRI comes back? Let's take a totally new path."

Peña Nieto navigated the attacks with solid rebuttals and tried to paint his two main opponents as taking the negative road (the fourth candidate, Gabriel Quadri, while considered by some to be the winner for a solid performance, mostly stayed out of the fray – though it helped that he was largely ignored by the other candidates). "They seem to have come to an agreement,” Peña Nieto said of the attacks by Vazquez Mota and Lopez Obrador. "They're coming with knives sharpened.”

One of the latest polls ahead of the debate, published in El Universal Sunday, put Peña Nieto ahead at 39.2 percent, Vazquez Mota at 22.1 percent, Lopez Obrador at 17.5 percent, and Mr. Quadri at 1.1 percent. In the leading papers in Mexico today, analysts disagreed over who the winner ultimately was, which means the race is probably going to be unaltered by the debate.

“The debate allows the candidates to present their ideas and how they will tackle issues if they become president, but it did little to influence the vote,” says Javier Oliva, an analyst at Mexico's National Autonomous University.

The format of the debate hails from an older idea that you can't touch the candidates – for one day one of them will be president, Mr. Oliva says. “I call them 'Soviet debates' ... It was not like the debate of Hollande and Sarkozy, which had more freshness,” Oliva says, referring to the candidates in France's recent election.

But it's not the format itself that made this debate so uninspiring, says Mr. Muñoz, it's the participants. Last election Lopez Obrador skipped out on one debate, which cost him crucial points. In 2000, when Vicente Fox of PAN won the presidency, his charisma behind the lectern caused him to soar.

“This time [debates] won't make the difference of a single point,” Muñoz says.